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Locked Correct button?
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Good question Ernst. Let me take a look and see if I can figure it out. I have a guess that it may have to do with the fact that the standards, open, short, load are NOT perfect. But... the softkey selection does not lead to additional menu selection. So far now, it appears to be a PLACE HOLDER for further work.
Alan ________________________________ From: [email protected] <[email protected]> on behalf of dk1vi <dk1vi@...> Sent: Sunday, July 28, 2019 11:44 PM To: [email protected] <[email protected]> Subject: [nanovna-users] Correct button? Hi, what is the purpose of the "CORRECT" button in the calibration menu? I have not read anything about it or did I miss something? Ernst |
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I would guess it is a mode switch between: 'Apply calibration corrections'
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and 'Don't apply calibration corrections' This feature is present in other VNA's. Am not in front of a device to confirm it though. Regards, Roger On Mon, 29 Jul 2019 at 13:06, alan victor <avictor73@...> wrote:
Good question Ernst. Let me take a look and see if I can figure it out. I |
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Good suggestion and it does appear to toggle in that manner.
Now, I have to think why I would toggle corrections ON and OFF, other than to see if the corrections ON make sense. I am not sure this is a good place to bring up the fact that the STANDARDS provided with the nanoVNA are taken, I believe, by the device and the firmware as IDEAL. Point in fact, they are NOT. Not an issue at lower frequencies unless you want to split hairs. But as you approach 900 MHz, bottom line, when measuring a component, you are not going to get the correct answer. I emailed the developer on this topic but as of now, no response. Alan ________________________________ From: [email protected] <[email protected]> on behalf of Roger Henderson <hendorog@...> Sent: Monday, July 29, 2019 1:10 AM To: [email protected] <[email protected]> Subject: Re: [nanovna-users] Correct button? I would guess it is a mode switch between: 'Apply calibration corrections' and 'Don't apply calibration corrections' This feature is present in other VNA's. Am not in front of a device to confirm it though. Regards, Roger On Mon, 29 Jul 2019 at 13:06, alan victor <avictor73@...> wrote: Good question Ernst. Let me take a look and see if I can figure it out. I |
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You are correct and I confirmed on the big box, that is the function performed.
This turns CAL ON or OFF. Again, I suspect hp as well others, added this function as an aid to be sure the correction data sets make sense as a corrective measurement is conducted on a component. Its much easier to do this then preset the instrument and have to do a complete re calibration. Alan ________________________________ From: [email protected] <[email protected]> on behalf of alan victor <avictor73@...> Sent: Monday, July 29, 2019 1:20 AM To: [email protected] <[email protected]> Subject: Re: [nanovna-users] Correct button? Good suggestion and it does appear to toggle in that manner. Now, I have to think why I would toggle corrections ON and OFF, other than to see if the corrections ON make sense. I am not sure this is a good place to bring up the fact that the STANDARDS provided with the nanoVNA are taken, I believe, by the device and the firmware as IDEAL. Point in fact, they are NOT. Not an issue at lower frequencies unless you want to split hairs. But as you approach 900 MHz, bottom line, when measuring a component, you are not going to get the correct answer. I emailed the developer on this topic but as of now, no response. Alan ________________________________ From: [email protected] <[email protected]> on behalf of Roger Henderson <hendorog@...> Sent: Monday, July 29, 2019 1:10 AM To: [email protected] <[email protected]> Subject: Re: [nanovna-users] Correct button? I would guess it is a mode switch between: 'Apply calibration corrections' and 'Don't apply calibration corrections' This feature is present in other VNA's. Am not in front of a device to confirm it though. Regards, Roger On Mon, 29 Jul 2019 at 13:06, alan victor <avictor73@...> wrote: Good question Ernst. Let me take a look and see if I can figure it out. I |
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I checked the code repo's posted and this is what I think the situation is
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with the standards: The load is assumed to be perfect - i.e. the assumption is that nothing is reflected from the load. The open is assumed to have a single C0 capacitance term of 50e-15F The short is either assumed to be perfect, or is assumed to be 180degrees away from the open. I am not quite sure on that. There is some unused code which looks to be intended to create a C0,C1,C2,C3 model of the open, but it is not used. Roger On Mon, 29 Jul 2019 at 14:37, alan victor <avictor73@...> wrote:
You are correct and I confirmed on the big box, that is the function |
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Thanks! That is helpful. The fact that the polynomial code to describe the open is present implies he was aware of the situation and at this point elected to put it aside. So for all intent and purpose, the loads are assumed to be ideal and that tends to agree with the final sweep to check the loads after cal. The check returns them to be IDEAL... And they are anything but ideal as that is the electrical-physical nature of a SMA connector.
Alan ________________________________ From: [email protected] <[email protected]> on behalf of Roger Henderson <hendorog@...> Sent: Monday, July 29, 2019 8:32 PM To: [email protected] <[email protected]> Subject: Re: [nanovna-users] Correct button? I checked the code repo's posted and this is what I think the situation is with the standards: The load is assumed to be perfect - i.e. the assumption is that nothing is reflected from the load. The open is assumed to have a single C0 capacitance term of 50e-15F The short is either assumed to be perfect, or is assumed to be 180degrees away from the open. I am not quite sure on that. There is some unused code which looks to be intended to create a C0,C1,C2,C3 model of the open, but it is not used. Roger On Mon, 29 Jul 2019 at 14:37, alan victor <avictor73@...> wrote: You are correct and I confirmed on the big box, that is the function |
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Hi Alan,
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I just want to point out that the polynomial + delay + impedance method for characterising standards is itself just an approximation. In this day and age (of cheap storage) it is simpler to just sweep the standards on a calibrated VNA, get an s-param file for each one and use that data in the calcs - with some interpolation for the in-between frequencies. This gives the highest accuracy as there is no modelling error. It also means you can use any old standard you like. The polynomial models don't fit poorly made standards very well over a wide frequency range, hence the need for high quality expensive parts. However I'm not sure if this device has the storage available to do it this way, if not the old school approach might be the best way. Regards, Roger On Tue, 30 Jul 2019 at 08:49, alan victor <avictor73@...> wrote:
Thanks! That is helpful. The fact that the polynomial code to describe the |
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Have you had an email come in from groups.io a week or so later and since there was no quoting you have no clue what the question was really about? Like this one, the subject line says "Correct button? That doesn't tell me anything. But since I'm quoting you, you and everyone else knows exactly what post I referring to.
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On Wednesday, November 16, 2022, 07:49:14 AM CST, Paul M3VUV <nanovnauser@...> wrote:
well , had this question as well but after reading thru this lot,it still doesent to anwer the original question,its harder to understand when ppl quote what been said already in the thread,just makes it a confusing mess to try and read!!. |
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I would agree that being able to use a "externally measured" cal standard data file (.s1p or .s2p) would be the preferred approach, and is supported in, e.g. nanovna-saver.
Whether you'd want to do that *in* the NanoVNA itself is really more about space available, time required for implementation, testing, etc. I'm pretty happy with the "box" as a sensor with basic functionality and the assumption of ideal standards - it gets me to within a few percent. If I need better, I'd rather have that in an external system with a lot more resources. When looking at what I'd want firmware developers to look at, it's things "internal to the box" - improved sampling, filtering, etc. - those are things that cannot be done in an external device. Some are hardware wishes (easier to bring the reference receiver input out, so I can use an external bridge. More flexibility with signal levels. But more sophisticated calibration seems something that is better pushed to a post processing or application. That's what I've done for years with other VNAs and similar equipment. I can have an infinite number of calibration schemes on a pc, manipulate them to my own needs, etc. |
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Paul, aren't we easily triggered by nothing? That was pretty rude. I have to agree with Max that when someone posts a reply without the prior comment it makes too hard to follow the request for help, thereby eliminating what could be solutions from experts who are too busy to otherwise take the extra time to figure out what the reply topic is about. You may have that time, but then you may not have the best solution to offer, which is at best may leave the other folks without that solution they're looking for. Try to be more understanding...and polite here.
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Stephen W9SK -----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Paul M3VUV Sent: Wednesday, November 16, 2022 8:55 AM To: [email protected] Subject: Re: [nanovna-users] Correct button? max may i suggest unless you are going to answe the original question keep your mouth shut and hands away from the keyboard,seems you can do neither!. |
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Stephen
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Thank you very much for this reply.? That needed to be said.? Well done. Don KC1MPO On 11/16/2022 12:21 PM, Stephen W9SK wrote:
Paul, aren't we easily triggered by nothing? That was pretty rude. I have to agree with Max that when someone posts a reply without the prior comment it makes too hard to follow the request for help, thereby eliminating what could be solutions from experts who are too busy to otherwise take the extra time to figure out what the reply topic is about. You may have that time, but then you may not have the best solution to offer, which is at best may leave the other folks without that solution they're looking for. Try to be more understanding...and polite here. |
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Ironically I have no idea who this is directed at or even what the original question was due to lack of message quoting. Not that I care, I just got a good chuckle out of it....
73 -Jim NU0C On Wed, 16 Nov 2022 08:54:59 -0800 "Paul M3VUV " <nanovnauser@...> wrote: max may i suggest unless you are going to answe the original question keep your mouth shut and hands away from the keyboard,seems you can do neither!. |
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"max may i suggest" NO YOU MAY NOT!? Do you always blow a fuse when you don't get what you want?Why would anyone answer you acting like that??
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Good luck. Max On Wednesday, November 16, 2022, 10:55:11 AM CST, Paul M3VUV <nanovnauser@...> wrote:
max may i suggest unless you are going to answe the original question keep your mouth shut and hands away from the keyboard,seems you can do neither!. |
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Just ignore it. Many issues with email, but usually not important. I get emails a month later sometimes. I get them quickly on my iPhone and then get the same ones days later on my iPad¡ go figure.
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David J. Wilcox¡¯s iPad On Nov 16, 2022, at 10:48 AM, Max via groups.io <kg4pid@...> wrote: |
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Paul,
This was properly answered in a much earlier post in this thread, go back and read it: /g/nanovna-users/message/588 In later versions of the firmware, this has been re-labeled "APPLY", with a checkmark when selected, making it a bit more clear that this function simply applies the calibration, or allows the calibration to be disabled. |
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I am going to lock this thread. If the OP needs more information about the original topic, please start a new thread.
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DaveD, co-owner On 11/16/2022 10:20 PM, Max via groups.io wrote:
"max may i suggest" NO YOU MAY NOT!? Do you always blow a fuse when you don't get what you want?Why would anyone answer you acting like that? --
This email has been checked for viruses by Avast antivirus software. www.avast.com |
Stephen W9SK
Jim Shorney
David Wilcox K8WPE
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